Aqueous co-emulsions of epoxy resin and mineral oil

ABSTRACT

An aqueous emulsion of epoxy resin or epoxy resin solution and mineral oil can be formed using a low level of predominantly non-ionic surfactant and an anti-static agent.

FIELD OF THE INVENTION

This invention relates to the field of aqueous emulsions, particularlyto the field of aqueous emulsions of epoxy resins, and more particularlyyet to the field of aqueous emulsions of epoxy resins stabilized withsubstantially non-ionic surfactants and suitable for use in formulatingsizing compositions for glass fibers.

BACKGROUND OF THE INVENTION

Aqueous emulsions of epoxy resins have long been known and used, e.g. informulating adhesives, coatings, etc. In particular they have found usein formulating sizing compositions for glass fibers which are to beimbedded in a resinous matrix as mechanical reinforcement for articlesfabricated therefrom, especially where such resinous matrix is itself anepoxy resin and the article is a tank or pipe fabricated by windingessentially continuous strands of the sized glass fibers about asuitable mandrel while concurrently impregnating with the matrix resin.

It is a particular object of the present invention to provide an aqueousco-emulsion of epoxy resin and mineral oil adapted for formulatingimproved sizing compositions for glass fibers.

SUMMARY OF THE INVENTION

This invention is an aqueous emulsion consisting essentially of: (a)about 30 to about 75 weight percent, based on the total weight of theemulsion, of (i) an emulsified liquid epoxy resin or (ii) a liquidsolution containing a total weight of epoxy resin from about 30 to about75 percent of the total weight of the emulsion and an organic solventtherefor; (b) about 1 to about 5 weight percent, based on the weight ofthe epoxy resin, of mineral oil; (c) about 5 to about 12 weight percent,based on the weight of the epoxy resin, of predominantly non-ionicsurfactant for emulsifying the epoxy resin or solution thereof and themineral oil; (d) about 0.5 to about 5 weight percent, based on theweight of the epoxy resin, of an anti-static agent; and (e) water.

DESCRIPTION OF PREFERRED EMBODIMENTS

The epoxy resin component of the emulsion can be any resin having epoxyfunctionally, preferably having at least about 2 vicinal epoxide groupsper molecule thereof. In order that the epoxy resin emulsify easily andthat the emulsified epoxy resin be capable of forming a coherent filmupon drying the emulsion or an aqueous composition formulated therefromat ordinary ambient workplace temperatures, it is preferred that theepoxy resin either be liquid at such temperatures or be dissolved with asuitable solvent or plasticizer to form a solution which is liquid atsuch temperatures and which preferably comprises a major proportion byweight of epoxy resin and a minor proportion by weight of solvent orplasticizer.

Particularly suitable epoxy resins for many purposes are glycidylether-terminated adducts of bisphenols such as bisphenol F or bisphenolA with a molar excess of epihalohydrin. Those having low epoxyequivalent weight (EEW), e.g. not greater than about 250 and preferablyfrom about 175 to about 190, are especially advantageous, but epoxyresins with higher EEW's can also be used, particularly if aplasticizing solvent is also incorporated. Such plasticizing solvent forthe epoxy resins is most advantageously blended with the epoxy resinbefore its emulsification into the aqueous medium. A particularlysuitable solvent is diacetone alcohol, although others can be used ifdesired. A portion of the solvent, if any, may partition into theaqueous phase of the emulsion.

Even when an epoxy resin which is liquid at typical ambient workplacetemperatures is used, it may be found advantageous to dissolve it with aplasticizer or solvent in order to facilitate the preparation of theemulsion, and it may also be found advantageous to heat the liquid epoxyresin or the liquid solution of epoxy resin to facilitateemulsification. Of course, if it is desired that all or a substantialportion of such solvent or plasticizer remain in the product emulsion,e.g. for aiding subsequent coalescence to form a coherent film, thetemperatures to which mixtures containing the solvent or plasticizer areexposed during preparation of emulsions of the invention must beappropriately controlled.

The mineral oil component can be any mineral oil. Part or all of themineral oil may form a solution or cosolution with the epoxy resin orthe epoxy resin solution, respectively.

The surfactant for stabilizing the dispersion of the epoxy resin orepoxy resin solution and the mineral oil can be any suitablepredominantly non-ionic surfactant, but it will frequently be foundadvantageous to employ a predominantly non-ionic mixture of surfactants.Particularly advantageous non-ionic surfactants arealkylaryloxypoly(alkoxy)alkanols, especially C.sub.≧6-alkylaryloxypoly(C₂₋₄ -alkoxy)-C₂₋₄ -alkanols such as Igepal (TM/GAFCorp.) C0210, which is a nonylphenoxypoly(ethoxy)ethanol having an HLBindex of about 4.6, and Igepal (TM/GAF Corp.) C0890, or its 70% aqueoussolution Igepal (TM/GAF Corp.) C0897, which is anonylphenoxypoly(ethoxy)ethanol having an HLB index of about 17.8, andmixtures thereof. Minor proportions by weight of methylcellulose orsimilar material can also advantageously be included as part of thesurfactant system, as can minor proportions of anionic surfactants.

The anti-static agent can be any suitable material such as anamide/ester or a partial amide of a fatty acid and a polyalkylene aminewherein less than all of the amine groups of the polyalkylene amine havebeen amidified. It may in some circumstances be found advantageous to atleast partially neutralize any unamidified amine groups with a watersoluble weak acid, such as acetic acid.

The relative proportions of the various components of the emulsions ofthe invention should generally be within the following ranges, given inweight percents based on the weight of the total emulsion for the epoxyresin and epoxy resin solution and based on the weight of the epoxyresin for the other components:

Epoxy resin and solution--about 30% to about 75%, preferably about 45%to about 60%;

Mineral oil--about 1% to about 5%, preferably about 2% to about 3%;

Surfactant--about 5% to about 20%, preferably about 6% to about 12%, andmore preferably comprising, within either of these ranges, a majorproportion by weight of a non-ionic material havng an HLB index of about2 to about 7 together with minor proportions by weight of a non-ionicmaterial having an HLB index of about 15 to about 20 and ofmethylcellulose;

Anti-static agent--about 0.5% to about 5%.

While the proportions indicated are not narrowly critical, theadvantages to be derived from employing a lower that usual level ofsurfactant relative to the epoxy resin or solution thereof may not berealized if substantial departures from these proportions are made,especially as to the preferred upper limit of surfactant.

The emulsions of the invention can be prepared by conventionalprocedures. One particularly advantageous procedure is to first blendtogether the epoxy resin, solvent (if any), mineral oil, surfactant(except for methylcellulose or similar material), and anti-static agentto form a liquid mixture or solution. This mixture may advantageously beheated to a suitable temperature for fluidizing the mixture withoutexcessive volatilization of the components thereof, if desired. A diluteaqueous premix of methylcellulose or similar material at about the sametemperature is then slowly added to theepoxy-solvent-oil-surfactant-antistat blend with vigorous high shearagitation. Ordinarily a water-in-oil emulsion will form, but uponcontinued addition of the aqueous premix this will invert to anoil-in-water emulsion. Sufficient deionized water should then be addedto achieve the desired final concentration and, if the temperature issignificantly about ambient, the emulsion is mildly agitated while it iscooled to about ambient temperature.

Any suitable high shear mixing or agitating apparatus can be used.

EXAMPLE 1

A particularly advantageous emulsion of the invention has been preparedusing the following formulation:

    ______________________________________                                                           Wt. % of                                                   Material           total emulsion                                             ______________________________________                                        D.E.R. 330 epoxy resin                                                                           51.02                                                      Diacetone alcohol (DAA)                                                                          5.61                                                       Igepal CO 210      2.04                                                       Igepal CO 897      2.04                                                       Emerlube 7440      3.31                                                       Methocel A15LV     0.25                                                       D.I. water         Balance to                                                                    make 100                                                   ______________________________________                                    

D.E.R. 330 (TM/Dow) is a liquid glycidyl ether-terminated bisphenolA/epichlorohydrin adduct having EEW of about 177-188. Igepal C0210 andC0897 (70% N.V.) are non-ionic surfactants identified herein above.Emerlube 7440 (TM/Emery Industries) is a blend of about 40% mineral oil,about 20% amide/ester anti-stat and about 20% surfactant in about 3:1ratio of non-ionic to anionic. Methocel A15LV (TM/Dow) ismethylcellulose.

The epoxy resin, diacetone alcohol, Igepal C0210 and C0897, and Emerlube7440 were blended together with moderate agitation by a Myers (TM) highshear mixer at ambient temperature, then heated to about 150° F. whilebeing subjected to vigorous agitation by increasing the speed of themixer. A premix of the methylcellulose in about 80 times its weight ofde-ionized water, also at about 150° F., was then slowly added, followedby the balance of the de-ionized water, while vigorous high shearagitation was continued and the temperature maintained at about 150° F.Inversion of the emulsion occurred before all of the premix had beenincorporated. The emulsion was agitated at a low speed setting of themixer while it was cooled to about ambient temperature. The product wasa stable aqueous emulsion exhibiting the characteristic bluish color ofsmall particle emulsions.

A sizing composition for glass fibers was prepared from this emulsion bydiluting it with water and mixing therewith an organosilane couplingagent and polyvinyl pyrolidone. When glass fibers sized therewith wereused to fabricate glass fiber reinforced epoxy resin articles, theyexhibited superior properties in such characteristics as processabilityof the sized glass fibers during fabrication, rapid and thorough wettingof the sized glass fiber by the epoxy matrix resin, and shear andtensile strengths of the reinforced epoxy articles fabricated therefrom.

Numerous variations and modifications within the spirit of the inventionas specifically described and exemplified will be apparent to thoseskilled in the art and are contemplated as being within the scope of theinvention.

What is claimed is:
 1. An aqueous emulsion consisting essentially of: (a) about 30 to about 75 weight percent, based on the total weight of the emulsion, of (i) an emulsified liquid epoxy resin or (ii) an emulsified liquid solution containing a total weight of epoxy resin from about 30 to about 75 percent of the total weight of the emulsion and an organic solvent therefor; (b) about 1 to about 5 weight percent, based on the weight of the epoxy resin, of mineral oil; (c) about 5 to about 12 weight percent, based on the weight of the epoxy resin, of predominantly non-ionic surfactant for emulsifying the epoxy resin or solution thereof and the mineral oil; (d) about 0.5 to about 5 weight percent, based on the weight of the epoxy resin, of an anti-static agent and (e) water.
 2. An aqueous emulsion according to claim 1 wherein said non-ionic surfactant comprises a major proportion by weight of material having an HLB index of about 2 to about 7 and a minor proportion by weight of material having an HLB index of about 15 to about
 20. 3. An aqueous emulsion according to claim 2 wherein said non-ionic surfactant further comprises a minor proportion by weight of methylcellulose.
 4. An aqueous emulsion according to claim 1 wherein said non-ionic surfactant comprises a major proportion by weight of a C.sub.≧6 -alkylaryloxypoly(C₂₋₄ -alkoxy)-C₂₋₄ -alkanol having HLB index from about 2 to about 7 and a minor proportion by weight of a C.sub.≧6 -alkylaryloxypoly(C₂₋₄ -alkoxy)-C₂₋₄ -alkanol having HLB index from about 15 to about
 20. 5. An aqueous emulsion according to claim 4 wherein said surfactant further comprises a minor proportion by weight of methylcellulose.
 6. An aqueous emulsion according to claim 1 wherein said epoxy resin is characterized by an epoxy equivalent weight not greater than about
 250. 7. An aqueous emulsion according to claim 6 wherein said epoxy resin is a glycidylether-termintaed adduct of a bisphenol and an epihalohydrin.
 8. An aqueous composition according to claim 4 wherein said epoxy resin is characterized by an epoxy equivalent weight not greater than about
 250. 9. An aqueous emulsion according to claim 8 wherein said epoxy resin is a glycidylether-terminated adduct of a bisphenol and an epihalohydrin. 